Fatal error: Uncaught Error: Class "PHPUnit\Framework\TestCase" not found in D:\programs\xampp\htdocs\backend-test\vendor\google\cloud-core\src\Testing\System\SystemTestCase.php:38 Stack trace: #0 {main} thrown in D:\programs\xampp\htdocs\backend-test\vendor\google\cloud-core\src\Testing\System\SystemTestCase.php on line 38